Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
- Subject: Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
- From: email@hidden
- Date: Mon, 17 Feb 2003 11:59:55 EST
In a message dated 2/17/03 11:33:12 AM, email@hidden writes:
>
I calculated the color
>
error to see what colors are most affected, and by how much. For the test
>
I
>
am assuming you have a "perfect" sRGB monitor (i.e. its white point is
>
D65
>
and it has sRGB primaries) which is to be profiled with OptiCAL.
Not at all what I was comparing in my note, though I hope to have the chance
today to compare these particular variations visually...
As I have
>
stated before, there is no error in neutrals, and the errors increase as
>
the
>
color moves away from the neutral scale. It will be largest at the pure
>
sRGB
>
primaries. Here are the errors at the sRGB primaries:
>
>
R = 8.21 delta E
>
G = 11.16 delta E
>
B = 17.43 delta E
>
>
That corresponds with Ian's observations. These colors are not "beyond
>
the
>
general photo range,"
They had better be, or trying to stuff our photos inside the triangle of sRGB
(or AdobeRGB, which more or less shares two of these primaries) with these
values as its far corners will be doomed to failure. I generally consider any
image in sRGB or AdobeRGB with one or two of the values approaching 200, and
the remaining value(s) below 100 to be out of the general photo range (colors
with all three numbers high are near white, not highly saturated). The values
we are talking about here have one number at 255, and the other two at zero!
nor do I think errors of this magnitude would be
>
"indistinguishable."
Thats the difference between theory and empirical results; the concept of a
delta-e is useful until you extrapolate it to the edges of the range. I find
that a similar xy variation to be most visible in red primary, less in green,
and least in blue, to the degree that the delta-e values you note could
indeed indicate a variation that would be barely visible; and most visible in
in the red... Whether I find that to be the case won't be something I worry
much about until I have the two versions of the same monitor profile to
compare, as the theory doesn't mesh well with the reality.
C. David Tobie
Design Cooperative
email@hidden
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.